Pluvial Lake Palomas, Northwestern Chihuahua, Mexico, and Pleistocene Geologic History of South-Central New Mexico Reeves, Corwin C., Jr., 1965, Pp

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Pluvial Lake Palomas, northwestern Chihuahua, Mexico, and Pleistocene geologic history of south-central New Mexico Reeves, Corwin C., Jr., 1965, pp. 199-203 in: Southwestern New Mexico II, Fitzsimmons, J. P.; Balk, C. L.; [eds.], New Mexico Geological Society 16th Annual Fall Field Conference Guidebook, 244 p.

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PLUVIAL LAKE PALOMAS, NORTHWESTERN CHIHUAHUA, MEXICO AND PLEISTOCENE GEOLOGIC HISTORY OF SOUTH-CENTRAL NEW MEXICO C. C. REEVES, JR.

Department of Geosciences, Texas Technological College, Lubbock

Geologic study of the Lake Palomas basin is in its EXTENT AND DEPTH infancy. The writer first visited the area in the spring The extent of pluvial Lake Palomas is not fully of 1964. During the past year and a half emphasis has known because of a paucity of good topographic con- been on general reconnaissance, mapping of aban- trol in Mexico, fringing sand deposits, and a total doned shorelines, and geomorphological studies. This lack of subsurface control. Photogeologic maps, ground report lacks quantitative detail, but contains several and air reconnaissance, and the sketchy topographic geologic speculations based on legitimate geomorphic control available surprisingly do allow placement of evidence which have a direct bearing on the Pleisto- several well-developed abandoned shorelines. At least cene geologic history of south-central New Mexico. three abandoned beaches of regional extent are rec- Discovery of Lake Palomas and a high-water predeces- ognized, a 4,100-foot level termed the La Mota from sor verifies the presence of an early Pleistocene pluvial La Mota Rancho, a 4,070-foot level termed the Guz- lake surrounding the El Paso area, sheds new light man from Guzman playa, and a 4,030-foot level named on the mysterious La Mesa rounded gravels (Rube, the Las Muertos from the Las Muertos Mountains. 1962), and hopefully resolves the conflicting argu- Innumerable weak lower level beaches (fig. 2) also ments on the age of the Rio Grande Valley. exist, for instance, the Santa Maria at about 4,056 Lake Palomas is named for the village of Palomas feet and the El Sancho at about 4,010 feet. on the international border 35 miles south of Deming, The La Mota beach is best exposed along the New Mexico (fig. 1). Brand (1937) refers to Guzman, northeastern part of the basin, being more or less Santa Maria, and Tildio playas and the Franklin continuous from the vicinity of Columbus, New Mex- Bolson, and the term "Guzman Sink" is used by ico, south to past V. Ahumada, a distance of over 110 Martin (1963) for the northwestern part of the miles ( fig. 3). The La Mota beach is difficult to place Palomas basin. The Lake Palomas basin is not a sink accurately along most of the western flank of the and is today marked by several separated playas such basin because of Recent alluvial deposits. The best as Guzman and the Franklin Bolson or "El Barreal." approximation is the contact between Pleistocene la- Previous terminology is not only misleading but in- custrine and alluvial sediments and the Tertiary allu- correct. vial debris. The Lake Palomas basin extends from about the The Lake Palomas basin is split by upthrust Cre- Juarez-Chihuahua highway on the cast to about taceous block mountains and Tertiary extrusives on 107°30' W., and from the southern end of the Florida the north and east sides of Santa Maria playa (fig. 1). Mountains south to somewhat past Villa Ahumada The old western part of the lake is now marked by (fig. 1). Access to the basin is best provided by the the Guzman-Sabinal playas, the central part by the Juarez-Ascencion highway, which, although not paved, Santa Maria playa (fig. 4), and the eastern part by "El Barreal" (fig. 1). Thus, during high water stages allows all-weather travel. The old "Pershing Highway" of Lake Palomas, two islands existed: Santa Maria and south of Palomas is also generally passable except at Union, about 250 and 100 square miles in area, re- times during the rainy season (July-September). In- spectively. During the high water stages Lake Palomas numerable trails branch from the main road but most was about 130 miles long and in places 40 miles wide, are of the jeep type. Travel by car is best confined to definitely covering over 2,000 square miles and per- the main roads but most roads between the isolated haps as much as 3,500 square miles. The low level El ranchos are passable with a pickup. No automobile Sancho stage appears to have inundated at least 2,000 service or gasoline is generally available outside of square miles. Palomas, Ascencion, Juarez, or V. Ahumada, and Emory (1857) reported Santa Maria and Guzman good drinking water is impossible to find. Investi- playas joining in wet years but Brand (1937) thought gators are advised to prepare for any eventuality. this impossible. Field evidence indicates that both

200 NEW MEXICO GEOLOGICAL SOCIETY—SIXTEENTH FIELD CONFERENCE

I3ORNADO DEL/ 1 MUERTO

TULAI)FOSA

-- I BASIN !ALAMOGORDO s. 11;=.

3: MOUNTAIN AREAS

TOWNS AND/OR RCHOS...... ...... DEMING -,t:..... • < Florida .." PLAYAS AND/OR DRAINAGE f; Mts _ HUECO ae177 %WV BLSON Tres\ Westa Hermanas Potr/7$1---1-- Mts ■ mts I APPROXIMATE LA MOTA \ SHORELINE NEW MEXICO.4.•-"•::1:Potrillo Mt EL PASO 77, - S. MEXICO JUAREZ Boca Grande,. , ..• "•;1•1 I APPROXIMATE PRESENT Mts I POSITION OF 4,250- Guzman_ \\, FOOT CONTOUR ...... Playa / 0 La Motarfi_4%--/- -z_ Rancho "- EL. BARREAL Sabina/\ Las Muertosi Playa Guzman. Mts Santa Mario Playa

■■■ 9 10 20 30 MILES

108°001 107°00 I06°00 lq

FIGURE 1

Index map of south-central New Mexico and northwestern Chihuahua, Mexico. The south-pointing arrow 20 miles west of El Paso and immediately south of the international border marks the suspected ancestral Rio Grande influent to the Lake Palomas basin. The present position of the 4,250-foot contour marks the approximate minimum extent of ancient Lake Cabeza de Vaca. NEW MEXICO GEOLOGICAL SOCIETY-SIXTEENTH FIELD CONFERENCE 201

beach cut on the hard basalt rim on the north side of the Guzman-Santa Maria divide. The maximum thickness of lacustrine strata in the Lake Palomas basin is unknown. The Chihuahuan Desert is a flat plain broken by long narrow NNW- SSE aligned mountain ranges of mainly folded Cre- taceous strata and igneous intrusive and extrusive rocks. Between the ranges are long, narrow, and generally interconnected bolsones. The Chihuahuan bolsones, like La Mesa to the north, may be filled with many thousands of feet of unconsolidated debris and, as study of their northwestward trends in Arizona

FIGURE 2

Abandoned low level shorelines of pluvial Lake Palomas, north end of Guzman playa ( 31°18 N., 107°28 W.). Notice four levels.

FIGURE 4

Aerial photograph of Santa Maria playa, spring 1964 ( 31°9 N., 107°18 W.).

FIGURE 3

Aerial photograph of the Bonneville-Lahontan aged La Mota beach along northeastern flank of Lake Palomas basin ( 31°35 N., 107°15 W.). Notice regional extension of beach in background. Good exposure of lacustrine strata and wave-cut terraces in this locality.

were wrong. The Guzman and Santa Maria playas are at elevations of about 4,000 and 3,960 feet re- spectively,* the divide on the Guzman-Santa Maria trail rising only to about 4,050 feet. This effectively prevents joining of the playas during even the wettest years. However, both the Guzman and the La Mota FIGURE 5 Lake levels must have joined the playas during pluvial times. Figure 5 shows the faint trace of the Guzman North side of the Guzman-Santa Maria divide ( 31°10 N., 107°20 W.) showing the faint trace of the la Mota beach Both playas have an average slope of about 3 feet per mile. (arrows), pluvial Lake Palomas. 202 NEW MEXICO GEOLOGICAL SOCIETY-SIXTEENTH FIELD CONFERENCE shows, (Melton, 1965), perhaps with exaggerated ingly sooner or later joins in the debate over the age thicknesses of lacustrine strata. of the Rio Grande Valley (Lee, 1907; Dunham, 1935; Depth of Lake Palomas, at least above most of the Bryan, 1938; Kottlowski, 1953, 1958; Ruhe, 1962). present playas, was apparently never very great. The The writer is no exception, primarily because he feels La Mota beach is now only about 100 feet above that the significance of the presence of lakes de Vaca Guzman playa and only 140 feet above Santa Maria and Palomas in relation to the age of the Rio Grande playa. The deepest part of Lake Palomas was probably Valley is not altogether obvious. The characteristic in the Salinas de Union area (fig. 1) where the La rounded gravels of La Mesa arc of Kansan to medial Mota beach is about 410 feet above the playa (eleva- Illinoisian age (Hibbard, 1958; Strain, 1959). If they tion of Salinas de Union from Ciudad Juarez 13R-I, and underlying even-bedded clays. silts, and sands 1958). represent lacustrine strata deposited by Lake Cabeza de Vaca, no through-flowing pre-Kansan Rio Grande existed in the La Mesa or Tularosa-Hueco areas as AGE AND REGIONAL IMPLICATIONS suggested by Lee (1907) and Bryan (1938). This evi- Although no exact chronology has been established dence was also presented by Ruhe (1962: 1964). for Lake Palomas, certain gross assumptions, based on Strain (personal communication, May, 1965) be- related pluvial lake studies (Morrison, 1964; Broecker lieves the Rio Grande originally cut through Fillmore and Kaufman, 1965) and observed features, can be Pass and the Hueco Bolson, and abandoned its chan- made. The highest youngest abandoned shoreline, the nel in middle Pleistocene (post-medial Illinoisian?) La Mota, is considered to be of Bonneville-Lahontan time for its present course. Kottlowski (1958) sus- age (about 60,000 years B.P.), and the other lower pects meandering of the ancestral Rio Grande across shorelines perhaps to be reflective of late Wisconsin La Mesa south into Chihuahua before capture by high stands (Broecker and Kaufman, 1965). Evidence headward erosion of a lower Rio Grande in mid-Pleis- for a very old, early Pleistocene lake about 150 feet tocene time. The lowest part of the northeastern flank above the La Mota beach, generally in the form of of the Lake Palomas basin exists as a trough which escarpments and wave-notched mountain spurs, spo- may represent either an ancient Rio Grande influent radically occurs throughout the Lake Palomas basin. or a lake-fed effluent to an early Rio Grande Valley. An irregular remnant escarpment between Arena and This low trough extends north to La Mesa between the Potrillo Maar (Reeves arid De Hon, 1965) and El Paso and the East Potrillo Mountains (fig. 1) and, several truncated mountain spurs in the "El Barreal" from present physiographic evidence, is considered a area are thought to mark this old lake level. post-medial Illinoisian influent to the Lake Palomas Topographic maps show that a 4,250-foot lake level basin. The Rio Grande (after abandoning its course in the Lake Palomas basin would even now inundate through Fillmore Pass?) flowed west of the Franklin vast areas of southern New Mexico (fig. 1). La Mesa, Mountains into the Lake Palomas basin, perhaps as the Tularosa and Hueco basins, perhaps the southern long ago as late Illinoisian time or as recently as Jornada del Muerto, and the Rio Grande Valley as early Wisconsin. far south as the Ouitman Mountains must have been The abandoned ancient Rio Grande influent to inundated by the early Pleistocene lake waters. This the Lake Palomas basin, the present Mesilla Valley, area, combined with the larger area flooded in Chi- and the fact that the Bonneville-Lahontan La Mota huahua, means that the early Pleistocene lake sur- shore is not as high as old Lake Cabeza de Vaca, in- rounding the El Paso area covered about 9,000-10,000 dicate that northwestern Chihuahua lost the Rio square miles. Grande's flow probably in a manner not unlike that The idea of an ancient lake in the La Mesa-Tularosa- described by Kottlowski (1958), after medial Illinoisan Hueco areas is not new. Lee (1907) and Burrows time but before Bonneville-Lahontan time. This gives (1910) both thought, mainly from physiographic evi- a maximum of about 320,000 years and a minimum of dence, that gigantic lakes once covered much of north- about 60,000 years (Ericson, Ewing, and Wollen, western Chihuahua and southern New Mexico. Re- 1964) to entrench the Rio Grande. If we consider cently Rube (1962) and Strain (personal communica- 400 feet of entrenchment, a minimum cumulative tion, May, 1965), on the basis of rounded and flat- rate of 0.015 inches per year or a maximum cumulative pebble gravels, even-bedded sands and clays, and rate of 0.08 inches per year occurred. The maximum general topography, have proposed a Quaternary lake is not excessive considering the sediments incised. Be- in the El Paso area. Strain suggests the name Cabeza cause of the paired Tortugas, Picacho, and Fort Sel- de Vaca after the early Spanish explorer. den terraces along the Rio Grande (Ruhe, 1962, Everyone working in southern New Mexico seem- 1964), the late Illinoisan age seem most likely. NEW MEXICO GEOLOGICAL SOCIETY-SIXTEENTH FIELD CONFERENCE 20 3

Because of the absence of parallel abandoned shore- Bryan, Kirk, 1938, Geology and ground-water conditions of the Rio Grande depression in Colorado and New Mexico: in Rio Grande lines, a general southerly slope to the La Mesa gravels, Joint Invest. in Upper Rio Grande Basin in Colorado, New Mex- the mineralogy of the La Mesa gravels, many of which ico, and Texas: Natural Resources Comm., Washington Regional would tend to form beach-appearing pebbles regard- Planning pt. 6, p. 197-225. Burrows, R. II., 1910, Geology of northern Mexico: Bol. de la Soc. less of environment, and incorrect relative elevations Geol. Mexico, v. 7, p. 88-89. in northwestern Chihuahua, many investigators think Dunham, K. C., 1935, The geology of the Organ Mountains with it unlikely that early Pleistocene pluvial lakes inun- an account of the geology and mineral resources of Dona Ana dated the bolsones immediately surrounding El Paso County, New Mexico: New Mexico Bur. Mines and Mineral Res. Bull. 11, 272 p. and joined with the pluvial lakes in Chihuahua. It is Emory, W. H., 1857, Report on the United States and Mexican significant that both Strain (personal communication, boundary survey: 34th Congress, 1st Session, Senate Executive May, 1965) and the writer (often working nearly 100 Doc. 108. Ericson, D. B., Ewing, M., and Wollen, Goesta, 1964, The Pleisto- miles apart) find complementary evidence for Lake cene Epoch in deep sea sediments: Science, v. 146, p. 723-732. Cabeza de Vaca. Hibbard, C. W., 1958, Summary of North American Pleistocene Study of the Lake Palomas basin will continue with mammalian local faunas: Michigan Acad. Sci. Arts, Letters, Papers, v. 43, p. 3-32. emphasis placed on shoreline chronology, lacustrine Kottlowski, F. E., 1958, Geologic history of the Rio Grande near exposures, relation to ancestral drainage, and the an- El Paso: in Guidebook of Franklin and Hueco Mountains, Texas: cient Cabeza de Vaca level. Studies of interrelations West Texas Geol. Soc. 1958 Fall Field Trip, 91 p. between Lakes Cabeza de Vaca and Palomas will help , 1953, Tertiary-Quaternary sediments of the Rio Grande Valley in southern New Mexico: in Guidebook of southwestern to clarify the Pleistocene history of south-central New New Mexico: New Mexico Geol. Soc., 4th Field Conf., 153 p. Mexico. Lee, W. T., 1907, Water resources of the Rio Grande Valley in New Mexico: U.S. Geol. Survey Water Supply Paper 188, 59 p. Martin, P. S., 1963, The last 10,000 years, a fossil pollen record of ACKNOWLEDGMENTS the American Southwest: Univ. Arizona Press, Tucson, 87 p. Melton, M. A., 1965, The geomorphic and paleoclimatic significance The writer is particularly indebted to Dr. Guillermo of alluvial deposits in southern Arizona: Jour. Geology, v. 73, p. P. Salas, Director, Institute of Geology, National Uni- 1-38. versity of Mexico, Mexico City, for securing the co- Morrison, R. B., 1964, Lake Lahontan: geology of southern Carson operation of Petroleo Mexicanos and for supplying Desert, Nevada: U.S. Geol. Survey Prof. Paper 401, 156 p. Reeves, C. C., Jr., and De Hon, R. A., 1965, Geology of Potrillo the field control. Maar, New Mexico and northern Chihuahua, Mexico: Am. Jour. Sci., v. 263, p. 401-409. REFERENCES Ruhe, R. V., 1964, Landscape morphology and alluvial deposits in southern New Mexico: Annals Assoc. Am. Geol., v. 54, p. 147-159. Brand, D. D., 1937, The natural landscape of northwestern Chihua- , 1962, Age of the Rio Grande Valley in southern New hua: Univ. New Mexico Bull. 316, 74 p., 10 plates. Mexico: Jour. Geology, v. 70, p. 151-167. Broecker, W. S., and Kaufman, Aaron, 1965, Radiocarbon chronol- Strain, W. S., 1959, Blancan mammalian fauna from Rio Grande ogy of Lake Lahontan and Lake Bonneville II, Great Basin: Geol. Valley, Hudspeth County, Texas: Geol. Soc. America Bull., v. 70, Soc. America Bull., v. 76, p. 537-566. p. 375-378.